<template>
  <section id="thisColorPicker">
    <el-color-picker
      v-model="theme"
      :predefine="[
        '#409EFF',
        '#1890ff',
        '#0075FF',
        '#304156',
        '#212121',
        '#11a983',
        '#13c2c2',
        '#6959CD',
        '#f5222d'
      ]"
      class="theme-picker"
      popper-class="theme-picker-dropdown"
    >
    </el-color-picker>
  </section>
</template>

<script>
const version = require("element-ui/package.json").version; // element-ui version from node_modules
const ORIGINAL_THEME = "#0075FF"; // default color
import { mapGetters } from "vuex";
export default {
  data() {
    return {
      chalk: "", // content of theme-chalk css
      theme: "",
      oldTheme: ""
    };
  },
  mounted() {},
  computed: {
    ...mapGetters({
      sysTheme: "sysTheme"
    })
  },
  watch: {
    sysTheme: {
      handler: function(val, oldVal) {
        this.theme = val;
        this.oldTheme = oldVal;
      },
      immediate: true
    },
    async theme(val) {
      const oldVal = this.oldTheme ? this.oldTheme : ORIGINAL_THEME;
      if (typeof val !== "string") return;
      console.log(val, oldVal, "变了");
      const themeCluster = this.getThemeCluster(val.replace("#", ""));
      const originalCluster = this.getThemeCluster(oldVal.replace("#", ""));
      const $message = this.$message({
        message: "正在替换主题",
        customClass: "theme-message",
        type: "success",
        duration: 0,
        iconClass: "el-icon-loading"
      });
      const getHandler = (variable, id) => {
        return () => {
          const originalCluster = this.getThemeCluster(oldVal.replace("#", ""));
          const newStyle = this.updateStyle(
            this[variable],
            originalCluster,
            themeCluster
          );
          let styleTag = document.getElementById(id);
          if (!styleTag) {
            styleTag = document.createElement("style");
            styleTag.setAttribute("id", id);
            document.head.appendChild(styleTag);
          }
          styleTag.innerText = newStyle;
        };
      };

      if (!this.chalk) {
        const url = `https://unpkg.com/element-ui@${version}/lib/theme-chalk/index.css`;
        await this.getCSSString(url, "chalk");
      }

      const chalkHandler = getHandler("chalk", "chalk-style");

      chalkHandler();

      const styles = [].slice
        .call(document.querySelectorAll("style"))
        .filter(style => {
          const text = style.innerText;
          return (
            new RegExp(oldVal, "i").test(text) && !/Chalk Variables/.test(text)
          );
        });
      styles.forEach(style => {
        const { innerText } = style;
        if (typeof innerText !== "string") return;
        style.innerText = this.updateStyle(
          innerText,
          originalCluster,
          themeCluster
        );
      });
      this.$emit("change", val);
      $message.close();
    }
  },

  methods: {
    updateStyle(style, oldCluster, newCluster) {
      console.log(style, oldCluster, newCluster);
      let newStyle = style;
      oldCluster.forEach((color, index) => {
        newStyle = newStyle.replace(new RegExp(color, "ig"), newCluster[index]);
      });
      return newStyle;
    },

    getCSSString(url, variable) {
      return new Promise(resolve => {
        const xhr = new XMLHttpRequest();
        xhr.onreadystatechange = () => {
          if (xhr.readyState === 4 && xhr.status === 200) {
            this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, "");
            resolve();
          }
        };
        xhr.open("GET", url);
        xhr.send();
      });
    },

    getThemeCluster(theme) {
      const tintColor = (color, tint) => {
        let red = parseInt(color.slice(0, 2), 16);
        let green = parseInt(color.slice(2, 4), 16);
        let blue = parseInt(color.slice(4, 6), 16);

        if (tint === 0) {
          // when primary color is in its rgb space
          return [red, green, blue].join(",");
        } else {
          red += Math.round(tint * (255 - red));
          green += Math.round(tint * (255 - green));
          blue += Math.round(tint * (255 - blue));

          red = red.toString(16);
          green = green.toString(16);
          blue = blue.toString(16);

          return `#${red}${green}${blue}`;
        }
      };

      const shadeColor = (color, shade) => {
        let red = parseInt(color.slice(0, 2), 16);
        let green = parseInt(color.slice(2, 4), 16);
        let blue = parseInt(color.slice(4, 6), 16);

        red = Math.round((1 - shade) * red);
        green = Math.round((1 - shade) * green);
        blue = Math.round((1 - shade) * blue);

        red = red.toString(16);
        green = green.toString(16);
        blue = blue.toString(16);

        return `#${red}${green}${blue}`;
      };

      const clusters = [theme];
      for (let i = 0; i <= 9; i++) {
        clusters.push(tintColor(theme, Number((i / 10).toFixed(2))));
      }
      clusters.push(shadeColor(theme, 0.1));
      return clusters;
    }
  }
};
</script>

<style lang="less">
#thisColorPicker {
  .theme-message,
  .theme-picker-dropdown {
    z-index: 99999 !important;
  }

  .theme-picker .el-color-picker__trigger {
    height: 26px !important;
    width: 26px !important;
    padding: 2px;
  }
  .el-color-picker__trigger .el-icon-arrow-down:before {
    content: "\e7b5" !important;
    font-size: 18px;
  }
  .el-color-picker__trigger {
    border: none !important;
  }
  .el-color-picker__color {
    border: none !important;
  }
  .el-color-picker__color-inner {
    background-color: transparent !important;
  }
  .el-icon-arrow-down:before {
    color: #99b4ca;
  }
  .theme-picker-dropdown .el-color-dropdown__link-btn {
    display: none;
  }
}
</style>
